Has anyone read Sue Roaf's article on mechanical ventilation (MV) in the latest issue of GBM? This article suggests MV (including MVHR) is a health risk and that these systems are energy hungry, without acknowledging the energy benefits of airtightness and heat recovery. Taking the implications of the article to their logical conclusion, we should ditch measures to make buildings highly energy efficient eg Passivhaus and huddle round heaters in cold leaky buildings instead. The health study from the Netherlands looked at 'perceived' health impacts from MV and whilst it may be valid, I don't think we can throw away Passivhaus based on a single study.

The article cites the deaths of 25,400 older people in the UK from cold in winter 2010/11 and asks whether whole house MVHR would have been their salvation. I think in airtight buildings the answer is probably 'yes' and in well insulated airtight buildings definitely 'yes'.

The clear failing in this article and apparently in the thinking which supports it is that it appears to be based on a prejudice against MV without addressing the reasons why it is used. Without mentioning airtightness, without mentioning Passivhaus (where it is a requirement), the article is worthless.

My request is for better informed evidence based debate in GBM. I'd like to know what other members think, particularly on the issue of Mechanical Ventilation. I am not a particular supporter of MV, although I recognise that airtightness has a part to play in energy efficient buildings and that Passivhaus has a serous role in the future.

Coul Fi-Wi be the happy medium between the two approaches?

I too find Roaf's work less than satisfactory. This article appears to be mainly an attempt to sell her new book. Finding an author declaring "an important new book" about her own work seems a little bit over the top.

She refers to a 'Technical Report 14' that apparently supports her views and makes it sound independent. She completely fails to mention that she is an author of this too! It's perhaps worth noting that the report is focussed on older properties and says "Although the proposed heating strategy cannot reduce the energy consumption to the levels expected of newly built houses with modern standards of insulation, it can be used together with other technical upgrade measures". It also recommends greater ventilation.

She refers to an article that is not yet published, making it very difficult to judge. She also fails to mention that she is on the editorial board of the journal in which the article will appear. Again, hardly independent. When summarising criticisms apparently made in the article, she doesn't distinguish between those inherent in the systems, and those caused by faulty installation or operation and maintenance, which are quite different problems to my mind.

So I don't feel able to take an informed view of her article. But the points above, together with a whole sequence of non-sequitur and apparently rhetorical questions throughout the article mean that my instinctive emotional reaction to it is pretty negative.

I join piersadler in requesting a better standard of journalism in the Green Building Magazine.

I worked for a while in a building with natural ventilation (it had been designed so that there were large convection "stacks" internally). It worked very well and as you say wookey, is probably better for a non-passivehaus in terms of energy use.

What is beginning to annoy me is the way that MVHR seems to be being advocated by manufacturers as an energy saving measure for ordinary houses. I very strongly suspect that it's no such thing for the majority of houses in the UK, that are generally far from being adequately air tight.

Personally I'd like to see whether it would be possible to make a zero energy passive MVHR system, the snag being to find a way to make it work acceptably under all weather conditions. I may have to settle for just using PV to offset the power used by the fans.

Just read joe90's link. A nice idea. A bit surprised they see no advantage in running the heat recovery side of it when the outside temperature is above 9 degrees.

Thanks djh for recognising that my initial post was really about the standard of journalism rather than mechanical versus natural ventilation.
I think there is probably a lot to be achieved by replacing air conditioning with natural ventilation in many cases and I also agree with JDHarris that MVHR in buildings which are not sufficiently airtight is a very poor choice, but whatever the issues in the debate, lets have more evidence based and balanced arguments in GBM.